Pages are always maximized, browser size must be >= 1280 width

- The maximized enforcement is a bit of a hack, but will do for now.
  Preferably we'd work with mozwebqa directly to do this.
- The 1280 width might annoy people; if so, we can take it out.
  However, the appliance isn't supported at widths lower than 1280px,
  so it doesn't do much good for tests to be running below that rez.
Lint.